Add a compat dummy stdatomic.h used when threading is disabled

Adapted from the code by Rémi Denis-Courmont from VLC

This merges libav commit eb34d40354e2474517c9b9bd787e0dadc89c2a81.

Signed-off-by: Wan-Teh Chang <wtc@google.com>
Reviewed-by: wm4 <nfxjfg@googlemail.com>
Signed-off-by: James Almer <jamrial@gmail.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/configure b/configure
index 93df74503b..ee473b995e 100755
--- a/configure
+++ b/configure
@@ -6391,6 +6391,9 @@ if disabled stdatomic_h; then
     elif enabled pthreads; then
         add_compat atomics/pthread/stdatomic.o
         add_cppflags '-I\$(SRC_PATH)/compat/atomics/pthread'
+    else
+        enabled threads && die "Threading is enabled, but no atomics are available"
+        add_cppflags '-I\$(SRC_PATH)/compat/atomics/dummy'
     fi
 fi